One-loop weak corrections to $γ/Z$ hadro-production at finite transverse momentum

TL;DR

This work quantifies the impact of one-loop weak corrections on γ/Z hadro-production with finite transverse momentum across RHIC-Spin, Tevatron, and LHC. Using helicity amplitudes and full EW one-loop calculations with MS-bar renormalization, the authors show that cross-section shifts are modest at RHIC but parity-violating asymmetries can be substantial, while high-p_T Z production at Tevatron and LHC experiences notable negative corrections (up to ~-14% at the LHC). The findings highlight the necessity of including weak corrections in precision Drell–Yan–like analyses and reveal opportunities for parity-violation studies with polarized beams. Overall, the paper provides a framework and quantitative results essential for accurate predictions in high-energy hadron collisions.

Abstract

We illustrate the effects of one-loop weak corrections onto the production of neutral gauge bosons of the Standard Model at RHIC-Spin, Tevatron and LHC, in presence of quark/gluon radiation from the initial state. We find such effects to be rather large, up to ${\cal O}(10-20%)$ in typical observables at all such colliders, where the cross section is measurable, thus advocating their inclusion in precision analyses

Figures (6)

• Figure 1: Graphs describing processes (\ref{['procs_neutral']}) in the presence of one-loop weak corrections. The shaded blob represents all the contributions to the gauge boson self-energy and is dependent on the Higgs mass (we have set $M_H=115$ GeV). We neglect loops involving the Higgs boson coupling to the fermion line. The graphs in which the exchanged gauge boson is a $W$-boson are accompanied by those in which the latter is replaced by its corresponding Goldstone boson. There is a similar set of diagrams in which the direction of the fermion line is reversed, with the exception of the last graph, as here reversal does not lead to a distinct topology.
• Figure 2: The transverse momentum dependence of the $\gamma$-boson cross section in (\ref{['procs_neutral']}) as well as of the beam asymmetries in (\ref{['asymmetries']}) at NLO (large frames) and the size of the one-loop weak corrections (small frames, limitedly to case in which the latter is non-zero), at RHIC-Spin ($\sqrt s_{pp}=300$ and 600 GeV). Notice that the pseudorapidity range of either particle in the final state is limited to $|\eta|<1$.
• Figure 3: The transverse momentum dependence of the $Z$-boson cross section in (\ref{['procs_neutral']}) as well as of the beam asymmetries in (\ref{['asymmetries']}) at NLO (large frames) and the size of the one-loop weak corrections (small frames), at RHIC-Spin ($\sqrt s_{pp}=300$ and 600 GeV). Notice that the pseudorapidity range of either particle in the final state is limited to $|\eta|<1$.
• Figure 4: The transverse momentum dependence of the $\gamma$- and $Z$-boson cross sections in (\ref{['procs_neutral']}) at LO (top frame) and the size of the one-loop weak corrections (bottom frame), at Tevatron ($\sqrt s_{p\bar{p}}=2$ TeV). Notice that the pseudorapidity range of the jet in the final state is limited to $|\eta|<3$.
• Figure 5: The transverse momentum dependence of the $\gamma$- and $Z$-boson cross sections in (\ref{['procs_neutral']}) at LO (top frame) and the size of the one-loop weak corrections (bottom frame), at LHC ($\sqrt s_{pp}=14$ TeV). Notice that the pseudorapidity range of the jet in the final state is limited to $|\eta|<4.5$.